This was born in another thread when Relianttexan asked me "If your going to judge the colts run defense on how they played in the playoffs then why not judge our defense in yds allowed the last 13 games of the season in which they were ranked 12th not 23rd.Or how bout we judge them the last 10 games of the season in which they were a top 10 D." I had pretty much ignored that "fact" because I didn't think it was possible that it was true. So this whole post is basically an answer to that question, but because of the scope it entails, I felt it was worthy of its own thread. This post will probably come in several parts because I see it being a lengthy but worthy read.

There is no standard for comparing defenses. You can rank them a number of ways. Ranking them by points allowed doesn't always work because its possible that the team's offense puts them in a bad position. So then you turn to yards. But then you have those bend but don't break situations.

My first inclination, when I read this was to simply take last year’s games, subtract the first 3 games stats from the total stats. Then Divide that number by 13 to get the average of the last 13 games. Then multiply those numbers by 16 to account for a full season. And Yardage wise, I'm proud to announce our Texans would have finished 13th overall in total yards, 14th overall in Rushing yards and an astonishing 11th in passing yards. If only it were that simple.

In some areas of the country, yards do count in the outcome of the game. Certain states will award a win to a team if after an overtime period teams are still tied, they count trips inside the 20 yard line and then total yards to determine the winner of a playoff game. Alas that is H.S. football. In the rest of the football world, the object of the defense is to keep the other team from scoring and if possible score themselves. Since for the most part defensive scores are an anomaly (with a few exceptions) they don’t really figure into the quality of the defense (despite what any fantasy football player would tell you) we will disregard them for this discussion. Points can’t be that determining factor either though. That is because the defense doesn’t play in a vacuum. Some offenses have a tendency to put defenses in a bad situation, or leave them on the field forever. So if you can’t look at yards and you can’t look at points, what can you possibly look at to give you an accurate measure of a defense?

It was no surprise to me that total yards = points. Mathematically that’s easy to prove. That’s probably why it’s not the most useful stat to break down defenses with. But if you split up yards by total rushing yards and total passing yards rushing yards figure into the equation much more heavily than passing yards, in fact Passing yards is around the threshold of the critical value of r – meaning it just barely meets the criteria for a correlation. That is because unlike rushing (in which a failed carry results in negative, or 0 yards) a failed pass attempt doesn’t really show up in the passing yardage. It’s just not a very effective way to measure passing effectiveness (or pass defense effectiveness).

This leaves you with yardage. What do you consider? Total yardage? That doesn't make much sense to me. Especially considering that the Ravens had almost 15% fewer plays on defense than the Titans did. I think that leaves you with yards per play. But I had to look to make sure there was a statistical significance between yan yards per play and points. So here is what I did. I took several major categories and from each team for the 06 season and compared them to points against. I then took the correlation coefficient and ranked them to attain the most relevant statistics. Here is a look at what each of the following statistics tells us and its correlation coefficient:

(note. The closer the number to 0 the lower the correlation. )

Total Yards ( .757) - This obviously has a high correlation to points. But like points it really doesn’t tell us much. Because total yardage is divided into two separate categories and doesn’t measure the importance of run versus pass defense, nor does it tell us what components of each respective aspect of the game are most important. It’s not a bad way to rank total defense but doesn’t account for those defenses that give up a lot of yards while not giving up many points.

Rush yards allowed (.549) /Pass yards allowed (.332) – The odd thing about this is that passing yards had such a low statistical significance. As a sub discussion of total yards they are helpful, but given the difference in plays from scrimmage on one side of the ball or another which isn’t accounted for, they may not be much help either.

Yards / Play (rushing and passing combined) (.772) – This was slightly higher than just total yardage. It tells you on each play what a defense yields. It will tell you, overall how the defense faired. What it won’t tell you is how the run defense faired or how the pass defense faired. It is very similar to total yards in that aspect but it also accounts for the fact that some teams had 800 something plays while others had over 1000.

Yards per Carry (.506) – I split this up from Yards per pass for a reason. It is kind of like the inverse of the whole completion % problem. Teams that allow a team to run the ball for say 3.4 yards, if they give up more rushes will actually stay on the field longer than a team who gives up 4.4 ypc. The whole 3 yards and a cloud of dust, take time off the clock phenomenon may be playing tricks with the numbers here.

Yards per Pass Attempt (.612) – Think of these as the WHIP of football. Statistically almost as significant as total yards by themselves they give you a better idea of what a team does on a per play basis. Ideally you would be able to split them up to where they happen but that involves a ton of work just to collect the numbers. Because yards/catch is so similar among teams Yards/Pass attempt winds up with an almost identical number to comp%.

Comp% (.615) is a little different number. But every bit as valid. Maybe more so. Most teams in the league will rank about the same in completion percentage that they would YPA since most teams are with in 2.5 yards per reception. Completion % though was a huge difference.

There will always be people who rank defenses differently. It is an inherently subjective ranking. You can argue that injuries, or a few bad games, or a few good games will skew the numbers. Between eras it becomes even more difficult. With the passing game having evolved as it has over the last 50 years more plays get run in a game. If you were going to ask me to use two barometers to to rank defenses within a certain year (2006 specifically) I would use the rushing yards against and completion% against numbers. They are specific enough to tell you something about the two different aspects of the defense while being broad enough to be categorized. An example of a stat that doesn't do that would be the yards per catch against. It doesn't take into account the completion% which since each team has a pretty close yards per completion average, is a stat that definitely figures into the effectiveness of any passing game.

I haven’t run the numbers yet to see where the Texans stand in those categories (to eliminate bias when I finally answer the question) but I will in the morning and then I’ll finally answer the question I started out trying to answer.

Yards allowed is considered the standard when ranking defenses. I don't know where that puts the Texans, but that is most likely what the other poster was referring to. I have also heard the statement about being a top 10 defense the last half of the season on the radio a few times.

All of this stuff is nice, but how about just coming out and saying how you feel or if you want to make this a statistical analysis how about giving us the big uglies and some improvement points? Not you though as it has got to be pessimistic while using six sigma methodology that defines the Texans by numbers that fit nothing, but your battle black heart.

The Texans D got better last year. What they need to get better at is creating TO's and the amount of three and out's. Qualilty defenses control the pace of the game. Great teams control it on both sides of the ball.

Now, there are obviously a lot of flaws, but the conclusions I draw from this pseudo-statistical analysis are
- We were obviously having some problems getting started, which could be attributed to a new defensive scheme, players in new positions, and new players starting, particularly Mario and DeMeco.
- We obviously improved over the season. And the obvious comparison is between the two games against Indianapolis.
- But how much? While our rank against the run and pass over the rest of the season look impressive, it becomes somewhat less so when factoring in the level of competition.
- We did better than would be expected against the rush over the rest of the season, taking the teams’ average against the rest of the league as an “average” opposing defense (again I realize this is flawed because I didn’t calculate the average rank of the defenses our opposing teams faced, didn’t factor in the particular game situations – blow-out vs. close game, time of possession, etc.).
- We did about what would be expected for an “average defense” against the pass over the rest of the season.

Looking forward to seeing your results. But I'm hoping the D's performance this year will render this moot.

The thing about dropping your outlyers (the 1st 3 games) to re-rank ourselves from 23 to 13 is that you can't just do that with the Texans.

Firstly, we played some very powerful offensive teams in those first three weeks. Every schedule has hard games and easy games, and we had 3 very difficult games in the first 3 weeks. If you removed every teams 3 hardest games and recalculated, I bet we'd drop back towards 23rd very quickly

Secondly, games in the beginning of the season usually are played the hardest. Most teams are at full strength, are still vying for playoff contention, and come out guns blazing. Toward the end of the year, we had some pretty meaningless games (vs. CLE for example). Many of these games were used by coaches to examine potential starters for next year (see Chris Taylor). Throwing away meaningful games for meaningless garbage time games doesn't really tell the whole story

All in all I definately agree that our team had a much stronger D in the 2nd half of the year, but Im sure that could be said of a lot of temas if you remove their worst games and reanalyze their yardage

We've just got to sit back wait & see this year. I think everyone noticed the improvement we had on defense @ the end of the year, but above all, i think that was just mainly the defense beginning to gel. If Okoye has the impact we think he will, & mario takes that next step, we will be among the top 10, bar none.

** sits back & waits for a titans fan to come in here with a defensive TO stat saying they're a top 10 defense. **

That's true, gtexan. There are a lot of factors that aren't accounted for. I don't think it really takes a statistical analysis to know that the defense played better later in the season, but it's interesting to me. Maybe pose the question to the chron stats blogger and let him run with it.

Why is everyone giving this guy a hard time? Sure I pointed out flaws, but criticizing him for even doing th ework in the first place? Do you know how much work he put into this research? And then you blast him for trying to use stats/modeling to examine the team last year and predict this year?

I mean, what do you want all the posts to be?
"I feel the Texans are the best!"
"The defense looks better to me than it did last year"
"The offense looks worse to me"

How lame is that? Sure its great to have personal observations, but some of us love looking at numbers to sort of help us guage ourselves in comparison to other teams

Im sorry to most of you, but I don't trust too many of your "personal opinions" Too many people are way too optimistic or pessimistic, and it clouds your judgement. There are a few people who can take off the rose colored glasses, but the vast majorityleave 'em on all year long. And thats great, but thats why these sort of posts make so much sense--they give us a nonbiased look at our team.

Watching your team play against itself in camps is as close to meaningless as you can get. Its all relative. A team with an incredible D and a great O will stil have an O that gets beat up in camp. It doesn't mean their terrible, it just means the D is better. A team with a horrendous O and an even worse D will look like its got a great offense. Its all relative.

So texanmike, thanks for the post! I for one appreciate the time it took to do this. Hopefully the people who criticize will remember that not everyone feels the same way they do

Why is everyone giving this guy a hard time? Sure I pointed out flaws, but criticizing him for even doing th ework in the first place? Do you know how much work he put into this research? And then you blast him for trying to use stats/modeling to examine the team last year and predict this year?

I mean, what do you want all the posts to be?
"I feel the Texans are the best!"
"The defense looks better to me than it did last year"
"The offense looks worse to me"

How lame is that? Sure its great to have personal observations, but some of us love looking at numbers to sort of help us guage ourselves in comparison to other teams

Im sorry to most of you, but I don't trust too many of your "personal opinions" Too many people are way too optimistic or pessimistic, and it clouds your judgement. There are a few people who can take off the rose colored glasses, but the vast majorityleave 'em on all year long. And thats great, but thats why these sort of posts make so much sense--they give us a nonbiased look at our team.

Watching your team play against itself in camps is as close to meaningless as you can get. Its all relative. A team with an incredible D and a great O will stil have an O that gets beat up in camp. It doesn't mean their terrible, it just means the D is better. A team with a horrendous O and an even worse D will look like its got a great offense. Its all relative.

So texanmike, thanks for the post! I for one appreciate the time it took to do this. Hopefully the people who criticize will remember that not everyone feels the same way they do

No one is giving him a hard time man, but even without doing the research (& good research it is) everyone who watched us last year, should've noticed how our defense improved the tail end of the season. Where that puts us this year, no one can be sure until the season starts & all the other factors that you pointed out have been considered.

All of this stuff is nice, but how about just coming out and saying how you feel or if you want to make this a statistical analysis how about giving us the big uglies and some improvement points? Not you though as it has got to be pessimistic while using six sigma methodology that defines the Texans by numbers that fit nothing, but your battle black heart.

The Texans D got better last year. What they need to get better at is creating TO's and the amount of three and out's. Qualilty defenses control the pace of the game. Great teams control it on both sides of the ball.

I think this post pretty much nails the premise of this thread. I have a boss that is a master at manipulating the numbers to fit his agenda. I can smell it a mile away and this thread has the same stench to it.

Yards allowed is considered the standard when ranking defenses. I don't know where that puts the Texans, but that is most likely what the other poster was referring to. I have also heard the statement about being a top 10 defense the last half of the season on the radio a few times.

I think by the time this thread is over with, we'll have a new standard to measure defenses by.

The thing about dropping your outlyers (the 1st 3 games) to re-rank ourselves from 23 to 13 is that you can't just do that with the Texans.

Firstly, we played some very powerful offensive teams in those first three weeks. Every schedule has hard games and easy games, and we had 3 very difficult games in the first 3 weeks. If you removed every teams 3 hardest games and recalculated, I bet we'd drop back towards 23rd very quickly

Secondly, games in the beginning of the season usually are played the hardest. Most teams are at full strength, are still vying for playoff contention, and come out guns blazing. Toward the end of the year, we had some pretty meaningless games (vs. CLE for example).

Why is everyone giving this guy a hard time? Sure I pointed out flaws, but criticizing him for even doing th ework in the first place? Do you know how much work he put into this research? And then you blast him for trying to use stats/modeling to examine the team last year and predict this year?

I mean, what do you want all the posts to be?
"I feel the Texans are the best!"
"The defense looks better to me than it did last year"
"The offense looks worse to me"

How lame is that? Sure its great to have personal observations, but some of us love looking at numbers to sort of help us guage ourselves in comparison to other teams

Im sorry to most of you, but I don't trust too many of your "personal opinions" Too many people are way too optimistic or pessimistic, and it clouds your judgement. There are a few people who can take off the rose colored glasses, but the vast majorityleave 'em on all year long. And thats great, but thats why these sort of posts make so much sense--they give us a nonbiased look at our team.

Watching your team play against itself in camps is as close to meaningless as you can get. Its all relative. A team with an incredible D and a great O will stil have an O that gets beat up in camp. It doesn't mean their terrible, it just means the D is better. A team with a horrendous O and an even worse D will look like its got a great offense. Its all relative.

So texanmike, thanks for the post! I for one appreciate the time it took to do this. Hopefully the people who criticize will remember that not everyone feels the same way they do

Yes that was a quick note. The premise is simply why the frig are we having this pessimistic bs at the beginning of the season? I think it is great that someone puts time and effort into quantifying things, but where was it at the end of last season and why the need to post redundantly around one's lament?

No one is giving him a hard time man, but even without doing the research (& good research it is) everyone who watched us last year, should've noticed how our defense improved the tail end of the season. Where that puts us this year, no one can be sure until the season starts & all the other factors that you pointed out have been considered.

Those are fool's factors...

Saying that we played meaningless games is meaningless in itself...

Football is football....

Like the Texans are the only team that had meaningless games at the end of the year....What about teams that rest starters??? What about teams that had this player hurt, and this player suspended???What about the teams that played in rain and couldn't pass a lot so they were forced to run a lot skewing their rushing stats???? What about the fact that every team doesn't play every team???What about if David Carr is the opposing QB???? Everyone wasn't afforded that luxury!!!

These "factors" can go on and on....And the thing is, IMO, it gets more and more ridiculous...

I trust my eyes, and what my eyes saw last year was a team that started of tentative with a lot of young guys, no real veteran presences, no co-hesiveness--that found a beast in Demeco Ryans a playmaking MLB, A young talented Mario, Some good street pick-ups at DT, a talented young corner in Dunta who is really looking good so far; added a talented young DT...Weaver at SDE...A deeper LB core, A deeper slightly more talented DB core...

I'm not sure why we shouldn't expect an improved defensive product...After spending so many picks on the defensive side of the ball and their improved play over the course of the season I think it's merely pessimism that would make you think otherwise...

Yes that was a quick note. The premise is simply why the frig are we having this pessimistic bs at the beginning of the season? I think it is great that someone puts time and effort into quantifying things, but where was it at the end of last season and why the need to post redundantly around one's lament?